CN1720445B - Systems and methods for using x-ray emission for process monitoring - Google Patents

Abstract

The present invention provides a systems and methods for process monitoring based upon X-ray emission induced by a beam of charged particles such as electrons or ions. Concept as expressed herein.

Description

Systems and methods for using x-ray emission for process monitoring

technical field

The present invention relates to scanning electron microscopy, and in particular to measuring copper layer thickness and detecting voids.

Background technique

An integrated circuit is a very complex assembly with many layers. Various layers may include conductive and/or insulating materials, while other layers may include semiconducting materials. These different materials are arranged in a pattern, usually consistent with the intended function of the integrated circuit. The pattern also reflects the manufacturing process of the integrated circuit.

Integrated circuits are manufactured by a complex multi-step process that may include depositing photoresist material on a substrate or layer, selectively exposing the photoresist material by photolithography, and developing the photoresist material to Patterning is formed to define certain areas to be subsequently etched or otherwise processed. After patterning, different materials are processed, such as depositing a copper layer. A deposition step is usually followed after removal (eg, by chemical mechanical polishing) of the contact material. Grinding often results in various deformations, such as dishing or erosion.

Various metrology, inspection, and defect analysis techniques have been developed to inspect integrated circuits during manufacturing steps, that is, between successive manufacturing steps, whether combined with the manufacturing process (also known as in-line) inspection technology) or not (also known as offline (off line) detection technology). It is known that manufacturing defects may affect the electronic characteristics of integrated circuits, and deviations from the desired dimensions of the pattern may cause such defects to appear.

X-ray reflectivity (X-Ray Reflectivity, XRR) and X-ray fluorescence (X-Ray Fluorescence, XRF) are methods that use X-rays to determine film thickness. Different equipment manufacturers will sell equipment using these methods for Film thickness determination. One of these equipment manufacturers is Jordan Valley, an Israeli company that sells various equipment. The JVX 5200 measuring equipment sold by it can perform the above two methods.

It is also possible to use X-ray-based methods to detect holes in the film. At present, the known technical solutions in the industry can refer to the following patents and patent applications, and their full texts are incorporated here for reference: Mazor et al. U.S. Patent No. 6,556,652, entitled "Measurement of critical dimensions using X-ray"; U.S. Patent No. 6,535,575 issued by Yokhin, entitled "Pulsed X-ray reflectometer"; U.S. Patent No. 6,041,095 issued by Yokhin, entitled "X-ray fluorescence analyzer"; US Patent Application No. 2003/0156682 by Yokhin et al., titled "Dual-wavelength X-ray reflectometry".

X-ray spots are usually relatively large, for example, the JVX 5200 device will form a spot of about 18-30 microns when performing XRF, and a larger spot (due to glancing angle brightness) when performing XRR, Its length is about 2-8 mm. Such measurements require relatively large test panels (about 70 x 100 microns for XRF and about 150 x 2000-5000 microns for XRR).

Electron beam metrology and defect inspection equipment, such as scanning electron microscopes, typically measure surface features as well as surface defects and contaminants at high resolution. These devices form very small electron dots, typically on the order of a few nanometers in length. These e-beam metrology and defect detection tools cannot detect holes or measure the thickness of layers such as opaque layers, especially copper layers.

U.S. Patent Application Serial Nos. 10/242,496, 09/990,170, and 09/990,171 filed by Nasser-Ghodsi et al., entitled "Methods and system fordishing and erosion characterization," "Methods and system for defect localization," and "Methods and system for defect localization," respectively. Methods and system for void characterization" etc. have described existing methods and systems for analyzing copper thin films.

Nasser-Ghodsi in US Patent Application Serial No. 09/990,171 discloses a system and method for providing information about the location of voids in response to measurement calculations. It should be noted, however, that the aforementioned calculation-based systems and methods are susceptible to various errors due to measurement inaccuracies (eg, differences between measurement devices, different materials with different X-ray absorption and emission characteristics).

Contents of the invention

In various embodiments, the present invention proposes several systems and methods for process monitoring based on X-ray emission induced by charged particle beams (such as electrons or ions).

The system and method provide an image that affects X-rays emitted from a plurality of locations located within a region of a sample. A processor can generate the image and control the graphical representation and processing of the image.

In another embodiment, the present invention provides a system and method for process monitoring that can analyze cavities before they are filled with conductive material.

In yet another embodiment, the present invention provides a system and method for process monitoring that applies quantitative iterative calibration techniques to detected X-ray emissions.

Description of drawings

In order to understand the technology of this case and how it is implemented in practice, the preferred embodiment of this case will be described with non-limiting examples and with reference to the attached drawings, in which:

Figure 1 illustrates the reaction process between a sample and a charged particle beam and various information volumes;

Figure 2 illustrates a Scanning Electron Microscope (SEM) that can be used for process monitoring in accordance with the present invention;

Figure 3 illustrates a cross-section of a small portion of a sample;

Figure 4 illustrates a wafer containing many target points;

Figures 5a-5d illustrate exemplary target points;

FIG. 6 illustrates a method for finding a target point or an area according to an embodiment of the present invention;

7-9 are flowcharts illustrating a method for process monitoring in accordance with an embodiment of the present invention;

Figure 10 is an exemplary sample image that provides a color-coded representation of pore volume in accordance with an embodiment of the present invention.

Explanation of reference signs:

2 Primary electron beam 3 Thin information volume

4 Auger Electronics 5 Large information volume

6 Backscattered electrons 8 X-ray electrons

9 Objects 11 Interaction Points

12 Objective lens 14 EDX detector

16 Secondary electron detector 17 In-lens detector

18 apertures 20 samples

22 mirror stage 40 base material

41 empty hole 42 large padding

44 small parts 60 wafers

62 grains 64 target points

71' Hole 72 Substrate

73 target point 74 L-shaped conductor

75 Target Points 77 Target Points

79 copper layer 81 copper layer

82 First part 84 Additional part

86 holes

Detailed ways

The present invention relates to systems and methods for process monitoring to detect holes in thin layers, or to determine the thickness of thin opaque layers.

Figure 1 illustrates various interactive processes and various information volumes. An information volume is a space in which interaction steps take place and induce X-ray or electron scattering, which can finally be detected to provide information about the information volume.

The figure illustrates that secondary electrons 2 strike a sample 20 at an interaction point 11 . Therefore, secondary electrons 2 and Auger electrons (Auger electrons) 4 will diverge from a very thin information volume 3, while backscattered electrons (Back Scattered Electron, BSE) 6 and X-rays 8 will be emitted from a rather large The information volume 5 (deep even exceeding one micron) leaves the detected object.

It should be noted that the distribution of electrons within this rather large information volume 5 is not uniform. The electron flux will gradually decrease as the distance from the interaction point 11 increases.

An indication of the depth of the hole can be detected by irradiating the vicinity of the hole with electron beams of different energies.

FIG. 2 illustrates a Scanning Electron Microscope (SEM) 10 that can be used for process monitoring in accordance with an embodiment of the present invention. The SEM 10 includes an electron gun (not shown in the figure) for generating primary electron beams, a plurality of control and voltage supply units (marked as 11 ), an objective lens 12 and an EDX detector 14.

It should be noted that SEM 10 may also contain more than a single detector. SEM 10 may include at least one in-lens detector (such as optional secondary electron detector 16) and/or at least one external detector (eg, EDX detector 14). The SEM 10 may include different types of detectors, such as secondary electron detectors, backscattered electron detectors, narrowband X-ray detectors, and the like. Each detector may include a single sensing element, or may include an array of sensing elements. The detectors can be positioned to detect rays emanating in different directions.

In the SEM 10, the primary electron beam is guided through an aperture 18 (located within the selectively disposed in-lens detector 17) to be focused by the objective lens 12 to fall on a test sample 20. The primary electron beam interacts with the sample 20 and thus reflects or scatters various forms of electrons and photons, such as secondary electrons, backscattered electrons, Auger electrons, and X-ray quanta.

EDX detector 14 is positioned to detect at least a portion of the diverging X-rays. EDX detector 14 is a broadband X-ray detector that provides a spectrum of radiation that can be analyzed to determine which materials interact with the electron beam. The inventors of this case used various EDX detectors, such as ThermoNoran's EDX detector, which has a Phi-Rho-Z electronic carbon needle calibration program (named PHI-RHO-Z). The present inventors also applied other quantitative correction systems, such as ZAF analysis. Both the Phi-Rho-Z calibration program and the ZAF analysis convert the peak area of the X-ray intensity into a chemical value representing the elemental weight fraction of the elemental composition of the spectrum. These techniques compensate for various phenomena when samples made of various materials are analyzed by EDX.

A general description of an EDX analyzer using ZAF analysis is disclosed in US Patent No. 5,299,138 to Fiori et al., which is hereby incorporated by reference in its entirety.

The sample 20 is positioned on a stage 22 . During process monitoring, relative movement will be formed between the sample 20 and the primary electron beam 2, which includes mechanical movement of the sample, mechanical movement of other components of the SEM 10 and/or electronic detection of the electron beam 2, or a combination of movement and detection. Generally speaking, the mechanical movement is performed after finding a specific target point or a specific area, but it can also be performed while scanning the target point or area.

When a specific target or area needs to be detected, it is necessary to find out the specific target point or area. FIG. 6 depicts an exemplary finding process, illustrating the process 50 of finding an area or a target point. Process 50 begins at step 52 where the machine is moved to the vicinity of a specific target or area (optional). Step 52 is followed by step 54, which usually uses the field of view derived from the inaccuracy of the mechanical movement to acquire an image of the adjacent area by scanning the adjacent area within a capture window. Figure 5a depicts the aforementioned neighborhood, including the target point (which, when scanned sequentially, includes a void surrounded by oxide) and other voids 71' and L-shaped conductor 74. Step 54 is followed by step 56 where the image is processed to find the target point or area. Step 56 generally involves comparing a target point with a previously acquired target point image. Once the specific target point or area is found, a scanning window (usually significantly smaller than the capture window) is used for scanning. It should be noted that the signal to noise ratio (signal to noise ratio) and/or Or the reaction period of the EDX detector usually affects the size of the scan window.

SEM 10 is generally used to perform various process monitoring methods (such as methods 100-300 in this case diagram), but some steps may require the use of other equipment, such as optical detection equipment or during step 210 of method 200. Critical Dimension Scanning Electron Microscopy.

The SEM 10 can include additional electrodes and anodes positioned along the path of the charged particle beam, which can be connected to a galvanometer (which can assess the intensity of the charged particle beam) that interacts with the electrodes or anodes as part of the electron beam. The electron beam can also be directed to a specific target point (formed within the sample) in order to measure the beam intensity.

The SEM 10 includes a processor 8 that processes the detection signals and also controls the operation of the various components of the SEM 10. In general, the processor 8 has image processing and control capabilities. For example, processor 8 may determine how to process the detected X-ray emission and how to form an image.

The image forming step includes judging which colors and/or markings are required for various hole volume ranges, various plane thickness value ranges, target point thickness ranges, hole depth ranges, and the like.

FIG. 3 is a cross-section illustrating a small portion 44 of a sample 20 . The small portion 44 includes a substrate 40 surrounding a plurality of voids 41 and a large pad 42, each surrounded by, but not covered by, the substrate 40. The large pads and voids (which have been exaggerated in size for illustration) are made of conductive material, such as copper. The conductive material is deposited on an etched substrate 40 followed by a contact conductive material removal process 42 . It should be noted that in many cases, an intermediate barrier layer can be provided between the individual holes 41 and between the large spacers and the substrate 40 .

This process can result in voids and/or deformation of the top surface of the conductor. Such deformations include overetching, shallow dishing, and scratches, and are usually especially noticeable when the conductors are relatively large. This also occurs when the conductor is a pad or a long conductor line, but is less noticeable when the conductor is a small interconnect or a void. The term "big" here is defined relative to the size of the illuminated spot, reflecting the size of other objects (such as holes), or reflecting the influence of dimensional deformation depending on the function of the integrated circuit.

FIG. 4 illustrates a wafer 60 having a plurality of die 62 that may include a plurality of target points 64 . Each die 62 may include a single target point 64 , but typically includes a large number of target points 64 . When there are many target points 64, the process monitoring step may include selecting which target point to evaluate. Certain target points may be formed within the wafer secant between die, while other target points may be formed within the die. A scanned target point or area may include voids partially surrounded by silicone, but this need not be the case. The present inventors also scanned the wire portion and realized that other shapes of targets could also be scanned during the process monitoring step. Typical target points are further described in Figures 5a-5d.

In order to provide comparative values between different target points, the constituent materials should be the same, and preferably have the same appearance. The inventors of the present case found that the target points can be in any pattern. For example, copper voids surrounded by oxide can be chosen as target points. The choices are all related to manufacturing process characteristics (such as propensity to form holes, large objects affected by shoving, and the like).

Figures 5a-5c illustrate top views of different target points 70, 73, 75, while Figure 5d illustrates a cross-sectional view of target point 77. Target points 70, 73, and 75 are established after copper contacts are removed, while target point 77 includes copper contacts to be removed later. FIG. 5 a shows a target point 70 comprising a single copper void 71 surrounded by a substrate 72 . FIG. 5 b shows a target spot 73 , which includes a plurality of holes 71 surrounded by a substrate 72 and a portion of conductive wire 74 . FIG. 5c shows a target point 75 comprising a portion 76 of a wire surrounded by a substrate 72 . Figure 5d shows the target point 77, which includes a buried hole 71, an upper layer of copper 79, the substrate 72 and a possible first part 82 and an additional part 84, which are irradiated with electron beams of different energies. And formed. The vias are connected to the copper layer 79 and the lower copper layer 81 . The shapes of the first portion and the additional portion correspond to the presence or absence of a hole (such as the hole 86 in the cavity 71 ).

Fig. 5a also illustrates the neighborhood 68 of the target point 70, ie the area bounded by a capture window. The adjacent area includes other holes 71' and an L-shaped conductor. Each of Figures 5b-5c represents a scan window.

FIG. 7 is a flowchart illustrating the process monitoring method 100 . Method 100 begins at step 110 by receiving a sample (eg, sample 20 made of two or more materials). After step 110, step 120 is performed to determine which area or area (group) of the sample 20 is to be scanned. Typically the sample is a wafer, and each region contains several target points, which when scanned sequentially may include copper objects at least partially surrounded by other materials (such as silicon oxide substrates) (such as the empty holes in Figures 5a-5d). 71).

In general, especially when performing die-to-die comparisons, each die scans the same area, although this is not required.

Step 120 is followed by step 130 of finding the area. Finding an area may include steps 52-56 shown in FIG. 6, but again this is not required. For example, mechanical movement may not be required in some cases.

Step 130 is followed by step 140 to scan the localized area of the sample, for example to induce X-ray emission from a first portion of the sample, such as the relatively large information volume 5 of FIG. 1 or portion 82 or 84 of FIG. 5d.

The shape and size of the first portion are responsive to various properties of the sample, as well as various properties of the charged particle beam. For example, the penetrability of electrons is easily affected by the material of the vicinity of the interacting target point, the arrangement of materials in the vicinity, the electron energy of the primary electrons, the tilt angle of the electron beam, and the like.

Step 150 is performed after step 140 to determine the X-rays emitted from the first portion. This step may include detecting a portion of the diverging X-rays, with detection being affected by the position of the EDX detector, the path of illumination and the sensitivity of the EDX detector, and the like. As mentioned previously, the detection step can also be performed with multiple detectors. These detectors can be of the same type and characteristics, but the frequency response and sensitivity can vary.

After step 150, proceed to step 160, that is, provide the indication of the relevant steps. Step 160 may involve applying certain analytical correction techniques to the detected x-ray emissions. Alternatively, the evaluation step may include a die-to-die or die-to-database comparison. Grain-to-grain involves comparing the results of the current illuminated target point with the results of another previous target point. The inventors of the present case found it quite useful to compare the results of the currently irradiated part with the results of another target point excluded previously on the same wafer (or even the same die), that is, to change the various characteristics of the divergent X-ray radiation in the wafer pair. There will be variations from wafer to wafer and even die to die. Such characteristics may include copper density and the like.

Quantitative analytical calibration techniques may be Phi-Rho-Z calibration procedures and/or ZAF analysis that converts X-ray intensity peak areas to chemical values (which represent the elemental weight fractions of the elemental composition of the spectrum).

Step 160 may include comparing the current time with the estimated scatter. Estimated scatter is susceptible to an evaluated first part, and more specifically to the evaluation material contained within that first part, and/or to the evaluated arrangement of objects within that first part Influence.

According to various embodiments of the invention, the first part comprises at least objects made of different materials, such as conductive objects (such as holes, metal layer conductors connected to the holes), substrates, barrier layers and similar. The assessed first part content may reflect a substantially flawless first part, but this is not required. For example, it may reflect a typical first part. The evaluation step is susceptible to the design of the test sample and/or to previous measurements of other parts of the sample or even other samples. This evaluation step may involve destructive measurements of other parts of the sample or other samples, eg including measurements of cross-sections of the sample, or non-destructive measurements.

It should be noted that the evaluation of the first part is susceptible to one or more parameters affecting the shape or size of the first part, such as the energy of the primary electron beam, the tilt angle, and the irradiated sample. The present inventors used Monte Carlo based simulations to evaluate the X-rays emitted by a sample.

According to an embodiment of the present invention, step 160 may provide an indication reflecting the presence or absence of a hole in the first portion. The inventors of the present case have found that even relatively small holes can be detected. For example, pores whose total volume is a very small percentage of void volume. When the target point is irradiated with primary electron beams of different energies, or even at different inclination angles, the depth of the hole and the total volume of each target point can be determined quite accurately.

According to another embodiment of the present invention, step 160 may provide an indication of the shape of an object located in the designated area. The aforementioned marking requires multiple measurements at different locations within the object, which define a grid. Each measurement reflects the thickness of the object at a specific location. Thus, by measuring the thickness of a particular conductive spacer or other large object, the method will indicate whether the object is flat, deformed, dished, and the like.

According to an embodiment of the present invention, the method 100 may include an optional step 170 of evaluating a characteristic of a reference object. The reference object is usually a filled hole filled with the same conductive material as the detection object. Step 170 is followed by step 160, wherein the flag is also susceptible to the evaluation characteristic. In general, the aforementioned property is the thickness of the reference object.

Step 170 may include measuring a property of the reference object. This step involves making multiple measurements at different positions of the reference object, but may also involve only a single measurement. The inventors of the present application chose to measure the reference object at a location selected to provide an indication of the thickness of the reference object. This selection may include evaluating where there will be no holes and/or where the effect of the saucer is less. For example, in a known large reference object, holes are often close to an object's edge. Therefore, the location chosen by the inventors of the present case is closer to the center of the object. If the surface of the large reference object is likely to be deformed, additional measurements may be taken to provide a representative parameter of the thickness of the reference object.

FIG. 8 is a flowchart of a method 200 for process monitoring. The method 200 can analyze a sample in a multi-step monitoring manufacturing process. The method 200 begins at step 210 by obtaining a sample with void properties. The sample is made of at least one first material. In general, sample 20 is an integrated circuit having at least one substrate and may include multiple layers, including conductive layers. The sample can be made of many materials, but at least some of these materials need not interfere with the emission of X-rays and therefore are not located in the first part which emits X-rays. Voids can be etched in a substrate that is subsequently filled with a conductive material such as copper.

Step 210 is followed by step 220 of judging the characteristics of the pores. The identifying step may include identifying at least one dimension of the void, such as a bottom width, a top width, and an average height. The identifying step may include scanning the void with a critical dimension scanning electron microscope (CD-SEM), where the scanning may include normal incidence as well as oblique incidence. The identifying step may include optical measurements, such as those involving reflectometers, and may also include evaluating the void volume or cross section thereof by comparing measurements of the void to a population of previously measured voids. The discriminating step may also include mathematically analyzing measurements to provide a discriminated characteristic. One such method of mathematical analysis was developed by IBM and involves applying a mathematical equation (usually a polynomial of a certain order) to the measurement.

The discrimination step is susceptible to one or more measurements of one or more dimensions of one or more voids.

Step 220 is followed by fabrication steps during which the sample is provided into a fabrication facility to be processed and then returned to the X-ray inspection facility (eg, SEM 10 of FIG. 2 ). The processing step includes filling the voids, which may also include grinding or removing excess material, but this is not required. The present inventors performed some of the foregoing measurements on samples comprising a filled void and an overlying layer of conductive material. In such cases the inventors have found that the upper layer generally does not have holes. However, various phenomena below the upper layer, such as shallowing of the layer, cannot be monitored without removal of the contact material.

Accordingly, the method 200 includes a step 230 of receiving a sample comprising filling the treated voids with a second material, such as a conductive material, in particular a conductive material such as copper.

Step 230 is followed by step 240 of directing a beam of charged particles toward the sample to induce X-ray emission from a first portion of the sample at least partially covering the treated void. The first portion generally includes the treated void and its surroundings. Once holes appear, this first section needs to be expanded to cover more areas.

Step 250 is performed after step 240 to detect X-rays emitted from the first portion.

Step 250 is followed by step 260 of providing an indication of the process in response to the characteristics identified by the first portion of emitted detected X-rays and the void. According to different embodiments of the present invention, the mark can reflect whether there is a hole in the first portion, or the shape of the filled hole. The indication can reflect the thickness of the treated voids at different locations.

Method 200 is associated with a single hole. It should be noted that in accordance with an embodiment of the present invention, the method can also be used to monitor this step in response to multiple processed voids, each void connecting a different portion. Therefore, at least steps 230 and 240 need to be repeated for each hole that has been processed multiple times. The labeling step associated with the process is susceptible to the X-ray emission detected by the portion connected to each void and the properties of at least one void. In this case, a number of multiple measurements, which can be made in different ways, can provide an indication of the process. Each result can be interpreted independently, but this need not be the case, and it can be further processed (including statistically) to provide a different indication.

According to one embodiment of the invention, multiple results are processed to provide an image of the sample that is indicative of the measured X-ray emissions (in response to detected X-ray emissions from portions of the sample).

According to another embodiment of the present invention, the hole characteristics can be more precisely characterized after taking multiple measurements while varying various illumination or detection characteristics such as accelerating voltage, angle of incidence, detector position, detector sensitivity, and the like. defined. Accordingly, method 200 may include a further step (not shown, but should be performed after step 250) of altering the characteristics of the charged particle beam to provide a modified electron beam, and repeating steps 230 and 240, ie to induce X-ray emission of a second portion of the sample at least partially covering the treated void, and detection of X-rays emanating from the second portion. Step 260 may also be modified so that the designation for the process further reflects the detected X-ray emissions from the second portion.

According to yet another embodiment of the present invention, the method 200 includes applying an analytical correction technique to the detected x-ray emissions for process monitoring.

FIG. 9 is a flowchart of a method 300 of process monitoring. Method 300 begins with step 310 of receiving a sample made of multiple materials.

Step 310 is followed by step 320 of scanning a plurality of target points to induce X-ray emission from the plurality of target points and detecting X-rays emanating from the plurality of target points. A plurality of target points are located within a first region of the sample. Step 320 may include narrowband or broadband X-ray detection. Exemplary broadband X-ray inspections include EDX inspections. Narrowband X-ray detection involves detecting X-rays within a narrow frequency, which usually includes specific divergent lines of a selected element, such as the K-line or L-line of copper. Narrowband detectors are well known in the art, and some are described in US Patent Application No. 09/990,171 by Nasser-Ghodsi et al.

Each area is irradiated and its radiation is detected before moving on to the next area, but it is also possible to perform simultaneous irradiation of multiple target points and corresponding detection steps.

Step 320 may include finding a plurality of target points. The target point may include steps of method 50, but this is not required.

Step 320 is followed by step 330, where an image of at least one region of the sample is created to indicate a process state in which x-rays have been detected in response to the plurality of target points.

Step 330 may include processing measured X-ray emissions in response to at least two material properties at the target point. The process can be a Phi-Rho-Z calibration process and/or a ZAF process. The process may include performing x-ray emission measurements in response to the measured intensity of the charged particle beam.

The image can indicate at least one of the following: whether there is a hole in the sample, the depth of the hole, the volume of the hole, the shape deviation of the target point, or shallow dishing.

The image can contain symbols or colors, or a combination of both. Different sign measurements or a combination of both can be assigned to different hole volume ranges, assigned to different hole depth ranges, assigned to different target point flatness ranges, assigned to different target point thickness value ranges, and the like. The image 400 of FIG. 10 is formed by assigning different colors to different pore volumes. Fig. 10 is an exemplary window of a simulation program for estimating the radiation emitted by a first part, in particular a sample.

According to an embodiment of the present invention, the method 300 further includes the following steps: changing the characteristics of the charged particle beam (scanning multiple target points) to form a changed electron beam, and scanning multiple targets with the changed charged particle beam points, whereby additional X-ray emissions from the plurality of target points are induced; and the additional X-ray emissions are detected. In this case, the labeling for the process would be more responsive to the additional detected X-ray emissions.

It should be noted that one target point may be irradiated with an electron beam and a modified electron beam before irradiating another target point, but this is not required. For example, multiple target points may be irradiated by the (ie unaltered) electron beam before the electron beam is altered to form an altered electron beam.

According to another embodiment of the present invention, once a plurality of voids have been irradiated, a treated void must be found before each irradiation. Each processed void can be identified by taking an image of an evaluated neighborhood of the processed void and processing it. The image is generally obtained by scanning a sample within a capture window. Typically a processed aperture is scanned within a scan window smaller than the capture window.

According to another embodiment of the present invention, the designation related to the process is further influenced by a reference parameter, eg reflecting other measurements of processed voids, or reflecting an estimated detected X-ray emission.

The present invention can be practiced using known apparatus, methods and compositions. Accordingly, details of the foregoing apparatus, compositions, and methods are not described herein. In the previous description, disclosure of numerous specific details was presented to provide a thorough understanding of the invention. It is to be understood, however, that the practice of the invention is not limited to the foregoing specific details.

What has been shown and disclosed in this Summary of the Invention is only an exemplary embodiment and a few variations thereof. It should be understood that the present invention can be implemented in various combinations and environments, and should be changed or modified within the scope of the invention defined hereinafter.

Claims (60)

1. A method for process monitoring, the method at least comprising the following steps: receiving a sample made of at least two materials; scanning a plurality of target points to induce X-ray emission from a plurality of target points located within a first region of the sample; detecting x-rays emanating from the plurality of target points; and An image of at least a region of the sample is created indicating a state of the process in response to detected x-ray emissions from a plurality of target points. 2. The method of claim 1, wherein said step of detecting X-rays comprises at least broadband detection of diverged X-rays. 3. The method of claim 1, wherein said step of detecting X-rays comprises at least narrow-band detection of X-rays. 4. The method of claim 1, wherein said step of creating an image includes at least processing the measured x-ray emissions in response to at least two material properties of the target point. 5. The method according to claim 4, wherein said treatment comprises at least ZAF treatment. 6. The method of claim 1, further comprising monitoring the intensity of the charged particle beam, and processing the x-ray emission measurements in response to the intensity. 7. The method of claim 1, further comprising the step of finding said plurality of target points. 8. The method of claim 7, wherein the step of finding a point of interest comprises at least obtaining an image of an estimated neighborhood of the point of interest, and processing the image to find the point of interest. 9. The method of claim 8, wherein the image is obtained by scanning the sample within a capture window. 10. The method of claim 9, wherein the target point is scanned within a scan window smaller than the capture window. 11. The method according to claim 10, wherein said one target point comprises at least one first object made of a first material, said first object is made of a second material Partially surrounded by the second object. 12. The method of claim 11, wherein the first object is a hole or an inline. 13. The method of claim 11, wherein the first material is a conductor. 14. The method of claim 11, wherein the first object is made of copper and the second object is made of silicon oxide. 15. The method of claim 1, wherein the image reflects the presence of holes in the sample. 16. The method according to claim 1, wherein the image can reflect the deviation in the shape of the target point. 17. The method of claim 16, wherein said deviation reflects shallowing. 18. The method of claim 1, wherein said image provides an indication associated with a volume of a void within each target point. 19. The method of claim 18, wherein different pore volume ranges are assigned different signs. 20. The method of claim 18, wherein different pore volume ranges are assigned different colors. 21. The method of claim 1, wherein the image provides an indication related to the flatness of each target point. 22. The method of claim 21, wherein different flatness ranges are assigned different symbols. 23. The method of claim 21, wherein different flatness ranges are assigned different colors. 24. The method of claim 1, wherein the image provides an indication related to the thickness of each target point. 25. The method of claim 24, wherein different thickness ranges are assigned different symbols. 26. The method of claim 24, wherein different thickness ranges are assigned different colors. 27. The method of claim 1, wherein said image provides an indication related to the depth of a hole within each target point. 28. The method of claim 27, wherein different hole depth ranges are assigned different symbols. 29. The method of claim 27, wherein different hole depth ranges are assigned different colors. 30. The method of claim 1, further comprising at least the step of modifying a characteristic of a charged particle beam scanning a plurality of target points to provide a modified electron beam. 31. The method of claim 30, further comprising at least scanning a plurality of target points with the altered charged particle beam, thereby inducing additional X-ray emissions from the plurality of target points, and detecting the additional X-ray emission. 32. The method of claim 31, wherein the process-related indicia is further responsive to the additional detected X-ray emissions. 33. A system for process monitoring, the system comprising at least: a scanning device for scanning a plurality of target points to induce X-ray emission from a plurality of target points positioned within a first region of a sample made of a plurality of materials; at least one detector for detecting X-rays emanating from the plurality of target points; and A processor for creating an image of at least a region of the sample indicative of a state of the process in response to detected x-ray emissions from the plurality of target points. 34. The system of claim 33, wherein said at least one detector is a broadband detector. 35. The system of claim 33, wherein said at least one detector is a narrowband detector. 36. The system of claim 33, wherein the processor processes the measured X-ray emissions to create an image responsive to at least two material properties of the target point. 37. The system of claim 33, wherein said processing comprises at least ZAF processing. 38. The system of claim 33, further comprising monitoring means for monitoring the intensity of the charged particle beam, and the processor is operable to process the x-ray emission measurements in response to the intensity. 39. The system of claim 38, wherein multiple target points can also be sought. 40. The system of claim 39, wherein finding a target point further comprises at least obtaining an image of an evaluated neighborhood of the target point, and processing the image to find the target point. 41. The system of claim 39, wherein the system acquires images by scanning a sample within a capture window. 42. The system of claim 41, wherein the system scans a target point within a scan window smaller than the capture window. 43. The system of claim 33, wherein said image reflects the presence of pores in the sample. 44. The system of claim 33, wherein the image reflects deviations in the shape of the target point. 45. The system of claim 33, wherein the deviation is reflective of shoveling. 46. The system of claim 33, wherein said image provides an indication relative to a void volume within each target point. 47. The system of claim 46, wherein said processor assigns different signs to different hole volume ranges. 48. The system of claim 46, wherein the processor assigns different colors to different hole volume ranges. 49. The system of claim 33, wherein the image provides an indication related to the flatness of each target point. 50. The system of claim 49, wherein the processor assigns different signs to different flatness ranges. 51. The system of claim 50, wherein different flatness ranges are assigned different colors. 52. The system of claim 33, wherein said image provides an indication related to the thickness of each target point. 53. The system of claim 52, wherein said processor assigns different symbols to different thickness ranges. 54. The system of claim 52, wherein said processor assigns different colors to different thickness ranges. 55. The system of claim 33, wherein the image provides an indication related to a depth of a hole within each target point. 56. The system of claim 55, wherein the processor assigns different symbols to different hole depth ranges. 57. The system of claim 55, wherein the processor assigns different colors to different hole depth ranges. 58. The system of claim 33, wherein a characteristic of a charged particle beam scanning a plurality of target points is further varied to provide a modified electron beam. 59. The system of claim 58, wherein a plurality of target points can also be scanned with the changed electron beam, thereby inducing additional X-ray emissions from the plurality of target points and detecting the additional X-rays. Ray emission. 60. The system of claim 59, wherein the process-related indicia is further responsive to the additional detected X-ray emissions.

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